The present invention relates to polyether.
An organic polymer has drawn an attention as a material for an insulating film of electronic devices and in order to make it usable for the insulating film, the organic polymer is required to be excellent in heat resistance, chemical resistance and having a low dielectric constant. Among the organic polymers, since polymers having an aromatic ring in its main chain and a thermosetting functional group in the side chain is excellent in heat resistance and chemical resistance, it is considered as a material useful for the insulating film.
For example, an organic polymer obtained by introducing vinyl group into the side chain of polyether sulfone and further modifying the vinyl group to ethynyl group is disclosed in Macromol. Chem. 185, 2319 (1984). Although this polymer is excellent in the heat resistance and the chemical resistance, its dielectric constant is not sufficient and therefore there has been desire for developing an organic polymer with a further decreased dielectric constant.
The object of the present invention is to provide an organic polymer excellent in heat resistance and chemical resistance and having a low dielectric constant as well.
The inventor of the present invention has enthusiastically made investigations to find an organic polymer free from such problems described above and consequently have found that polyether having ethynyl group is excellent in heat resistance and chemical resistance and having a low dielectric constant and have completed the invention.
That is, the present invention is to provide a polyether having a repeating unit of the following formula (1): 
(wherein R1 to R3 independently represent hydrogen atom, a halogen atom, or any substituent, or two of R1 to R3 may be mutually bonded to form a ring; R4 denotes a hydrogen atom, an alkyl group with 1 to 10 carbons which may be substituted, a cycloalkyl group with 6 to 10 carbons which may be substituted, an aromatic ring with 6 to 14 carbons which may be substituted, a trialkylsilyl group which may be substituted, or a hydroxyalkyl; and Ar represents a divalent aromatic group.).